The pulp manufacturing processes are roughly classified under three categories: timber cut-up, pulping and refining. Among these, the pulping process is the most important. According to the pulping method, produced pulp is classified as DP, KP, SP, SCP, GP, or MP. Among these, the KP type is the most used in paper manufacturing, and is produced in the greatest volume, preferred because of its quality, and cost advantages. Unlike the GP or MP method using mechanical Shearing force, the KP method mainly resorts to chemical treatment using a chemical agent (mix liquid of sodium hydrate and sodium sulfide solutions). Autoclaves are used in the pulping process for testing and studying digestion of various wood chips and yield measurement as well as bleaching/deinking of used paper, collection of chemicals and treatment of waste cooking liquid. This autoclave is easy to handle since the chamber and lid are made of stainless steel that can resist chemical corrosion even after long years of service.